Packed bed arrangement useful for mixing and/or oxidation

Abstract

The present invention relates to processes and apparatus for mixing oxidizable reactants with oxidant and/or oxidizing oxidizable reactants. Through using particular mixing and/or oxidizing arrangements, the risk of flammable or explosive reactions can be significantly reduced or prevented. When ammonia is used as the reactant, nitric acid can be obtained.

What is claimed is: 
     
       1. A process for oxidizing at least one oxidizable reactant selected from the group consisting of methanol, benzene, naphthalene, orthoxylene, cumene, methane, propylene, acrolein, hydrogen and ammonia with oxidant, said process comprising: mixing said reactant and oxidant in a packed bed containing inert packing materials, said inert packing materials being spherically shaped particles whose maximum diameter sizes are defined by the equation: ##EQU3## DP=diameter of inert spherical packing material (inch) VSD=superficial velocity at design inlet conditions (ft/sec) VLB=laminar burning velocity of mixture (ft/sec)   Dt=diameter of packed tube (inch)   or being non-spherically shaped particles whose maximum sizes are defined by the equation: ##EQU4## DP=diameter of inert spherical packing material (inch) VSD=superficial velocity at design inlet conditions (ft/sec)   VLB=laminar burning velocity of mixture (ft/sec)   Dt=diameter of packed tube (inch)   VP=volume of non-spherical packing materials (inch)   SP=surface area of non-spherical inert packing materials (inch 2 ) and subjecting the resulting mixture from said packed bed containing inert packing materials to an oxidation reaction condition to oxidize said reactant.     
     
     
       2. The process according to claim 1, further comprising introducing a temperature moderating means comprising water into said packed bed containing inert packing materials during the introduction of said reactant and oxidant to maintain the temperature below the autoignition temperature of the mixture. 
     
     
       3. The process according to claim 2, wherein said reactant is ammonia and wherein the amount of said ammonia and oxidant introduced is such that the concentration of ammonia in said mixture is at least about 15% by volume. 
     
     
       4. The process according to claim 3, wherein the amount of water introduced into said packed bed is within the range of about 0.5 tons to 0.9 tons of water per ton of said ammonia. 
     
     
       5. The process according to claim 3, wherein said resulting mixture is subject to oxidation catalysts in the form of a packed bed to oxidize the reactant therein. 
     
     
       6. The process according to claim 5, further comprising removing or recovering at least a portion of said heat from the oxidized reactant via a downstream waste heat boiler system. 
     
     
       7. The process according to claim 6, wherein said oxidized reactant comprises nitrogen oxides. 
     
     
       8. The process according to claim 7, further comprising condensing at least a portion of the nitrogen oxides thereof further in the presence of water to remove at least a portion of the nitrogen oxide in the form of nitric acid. 
     
     
       9. The process according to claim 1, wherein said oxidant has an oxygen concentration of at least about 25 percent. 
     
     
       10. A process for mixing at least one oxidizable reactant selected from the group consisting of methanol, benzene, naphthalene, orthoxylene, cumene, methane, propylene, acrolein, hydrogen and ammonia with oxidant, which comprises mixing said oxidizable reactant and oxidant in a packed bed containing inert packing materials wherein said inert packing materials are spherically shaped particles whose maximum diameter sizes are defined by the equation: ##EQU5## DP=diameter of inert spherical packing material (inch) VSD=superficial velocity at design inlet conditions (ft/sec) VLB=laminar burning velocity of mixture (ft/sec)   Dt=diameter of packed tube (inch) or said inert packing materials are non-spherically shaped particles whose maximum sizes are defined by the equation: ##EQU6## VSD=superficial velocity at design inlet conditions (ft/sec) VLB=laminar burning velocity of mixture (ft/sec)     Dt=diameter of packed tube (inch)   VP=volume of non-spherical inert packing materials (inch 3 )   SP=surface area of non-spherical inert packing materials (inch 2 ).   
     
     
       11. The process according to claim 10, wherein said inert packing materials are non-combustible materials selected from the group consisting of ceramics, gravel, sand, glass beads, limestone and combinations thereof. 
     
     
       12. The process according to claim 10, wherein said inert packing materials are non-combustible materials which are endothermic. 
     
     
       13. The process according to claim 10, further comprising introducing a temperature moderating means comprising water into said packed bed during the introduction of said reactant and oxidant. 
     
     
       14. The process according to claim 10, wherein said oxidant has an oxygen concentration of at least about 25 percent. 
     
     
       15. The process according to claim 10, further comprising indirectly cooling said packed bed containing inert packing materials.